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BioMed Research International
Volume 2016 (2016), Article ID 8905675, 9 pages
http://dx.doi.org/10.1155/2016/8905675
Research Article

Identification of Five Novel Salmonella Typhi-Specific Genes as Markers for Diagnosis of Typhoid Fever Using Single-Gene Target PCR Assays

1Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia
2Department of Medical Microbiology and Parasitology, Universiti Sains Malaysia (USM), Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia
3Faculty of Applied Sciences, AIMST University, Jalan Bedong-Semeling, 08100 Bedong, Kedah, Malaysia

Received 22 June 2016; Revised 27 September 2016; Accepted 18 October 2016

Academic Editor: Hao-Teng Chang

Copyright © 2016 Yuan Xin Goay et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Salmonella Typhi (S. Typhi) causes typhoid fever which is a disease characterised by high mortality and morbidity worldwide. In order to curtail the transmission of this highly infectious disease, identification of new markers that can detect the pathogen is needed for development of sensitive and specific diagnostic tests. In this study, genomic comparison of S. Typhi with other enteric pathogens was performed, and 6 S. Typhi genes, that is, STY0201, STY0307, STY0322, STY0326, STY2020, and STY2021, were found to be specific in silico. Six PCR assays each targeting a unique gene were developed to test the specificity of these genes in vitro. The diagnostic sensitivities and specificities of each assay were determined using 39 S. Typhi, 62 non-Typhi Salmonella, and 10 non-Salmonella clinical isolates. The results showed that 5 of these genes, that is, STY0307, STY0322, STY0326, STY2020, and STY2021, demonstrated 100% sensitivity (39/39) and 100% specificity (0/72). The detection limit of the 5 PCR assays was 32 pg for STY0322, 6.4 pg for STY0326, STY2020, and STY2021, and 1.28 pg for STY0307. In conclusion, 5 PCR assays using STY0307, STY0322, STY0326, STY2020, and STY2021 were developed and found to be highly specific at single-gene target resolution for diagnosis of typhoid fever.